KR20070094032A - Metallic powder blends - Google Patents

Abstract

After changing with the particle of the shape, it from under milling cadence proposal existing the additional additive and follows the basis powder in the process which it pulverizes and the even mouth light D50 which is manufactured below 75mum, is good and the metal and the alloy below 25mum or it is regarding the formation product which is manufactured with use and this blend of the composition powder and these powder blend.

Description

Metal Powder Mixture {METALLIC POWDER BLENDS}

The present invention provides an average particle diameter D50 of 75 μm or less, produced by the process of first transforming a base powder into flake-like particles and then grinding it with additional additives in the presence of a milling aid. Preferably a mixture of metals, alloys or composite powders of 25 μm or less, the use of these powder mixtures, and molded articles made from these mixtures.

According to International Application No. PCT / EP / 2004/00736, which has not yet been published for public viewing, from a base powder with a large average particle diameter using a Microtrac® X100 particle size analyzer according to ASTM C 1070-01 When measured, a powder obtainable by a process for producing a metal, alloy or composite powder having an average particle diameter D50 of 75 μm or less, preferably 25 μm or less is known, and the particles of the base powder have a particle size versus particle thickness. The flake shaped particles with a ratio of 10: 1 to 10000: 1 are treated in the deformation step, and these flake shaped particles are subjected to pulverisation or high energy loads in the presence of milling aids in further processing steps. It is advantageous to follow this process followed by a de-agglomeration. This flocculation disintegration step, in which powder agglomerates are broken into their primary particles, can be carried out, for example, in a gas countercurrent mill, ultrasonic bath, kneader or rotor-stator. In the specification of this patent, such powder is referred to as PZD powder.

Such PZD powders have, for example, better strength, oxidation and corrosion properties of the molded articles produced, compared to conventional metal, alloy and / or composite powders applied with powder metallurgy, as well as lower production costs, as well as green strength and compressibility. , Sintering properties, large sintering temperature range and / or low sintering temperature, have various advantages. The disadvantage of such powders is, for example, poor flowability. Changes in shrinkage properties associated with low tap densities can cause problems during powder metallurgy processes, resulting in greater sinter shrinkage. This powder feature is disclosed in International Application No. PCT / EP / 2004/00736, referenced herein.

Conventional powders obtained by, for example, atomization of metal melts also have disadvantages. In particular, certain alloy compositions known as high-alloy materials lack sintering activity, poor compressibility, and high manufacturing costs. These drawbacks are less particularly in metal injection molding (MIM), slip casting, wet spraying and heat spraying coatings. Due to the poor holding strength of conventional metal powders (abbreviated as "MLV" in the context of metals, alloys and composite powders), these materials do not have sufficient strength for the green compact to do so. It is inappropriate for conventional powder metallurgy compaction, powder rolling, and cold isostatic pressing (CIP) following the holding process.

An object of the present invention is a powder which does not have the above-mentioned disadvantages of conventional metal powder (MLV) and PZD powder but which can take full advantage of the individual advantages such as high sintering activity, good compressibility, high holding strength, good injectability, etc. It is to provide a metal powder for metallurgy.

Another object of the present invention is to provide a functional additive capable of supplying a molded article made from PZD powders with characteristic properties, such as additives that increase impact strength or wear resistance, such as super-strength powders, or to facilitate processing of shaped bodies. It is to provide a powder containing an additive, or an additive that functions as a template for controlling the porous structure.

It is a further object of the present invention to provide a high alloy powder that can be applied to all ranges of powder metallurgy forming processes and thus also applicable to fields which were not possible with conventional metals, alloys or composite powders.

This aim is to treat particles of the base powder having a large or small average particle diameter in the deformation step with flake shaped particles having a ratio of particle size to particle thickness of 10: 1 to 10000: 1, and these flake shaped particles are subjected to further processing steps. Measured using a Microtrac® X100 particle size analyzer according to ASTM C 1070-01, obtainable by a process of exposing to a grinder in the presence of a milling aid at To a metal powder mixture containing component I, which is a metal, alloy or composite powder of less than or equal to 25 μm or 75 μm, component II, which is a conventional metal powder (MLV) to be applied to powder metallurgy, and / or component III, which is a functional additive. Is achieved. Flaking preparation and grinding steps can be combined directly in the same unit by performing another step immediately after carrying out one step under conditions suitable for a particular purpose (flake formation, grinding).

This object is also aimed at measuring the shrinkage of a metal, alloy or composite powder using an dilatometer according to DIN 51045-1 within the temperature of the first shrinkage maximum, with the same chemical composition and the same average particle diameter D50 produced by atomization, Conventional components for powder metallurgy, component I, which are metals, alloys or composite powders that are at least 1.05 times larger than the shrinkage of the alloy or composite powder, and which have been shrunk to a compressive density of 50% of the theoretical density prior to measuring the shrinkage. A metal powder mixture containing component II, which is a metal powder (MLV), and / or component III, which is a functional additive. If the handle that can be handled cannot be made from conventional powders of the desired density (50%), greater densities can also be tolerated, for example by using pressing aids. This should be interpreted as meaning the "metal density" of the powder compact and not the average density of the MLV powder and the pressing aid.

The use of component I also makes it possible to produce metal powder mixtures in which the contents of oxygen, nitrogen, carbon, boron and silicon can be set accurately. If oxygen or nitrogen is injected into the process, high energy input can result in the formation of oxide and / or nitride phases during the manufacture of component I. These phases may be desirable in some applications because they can have significant material strengthening effects. This effect is known as oxide dispersion strengthening (ODS) effect. However, incorporation of such phases is often associated with lower processing properties (eg, compressibility, sintering activity). As a result of the general inert properties of the dispersoids for the alloy components, the alloy components can interfere with sintering.

Grinding is immediately finely distributed in the powders prepared above. Thus the formed phases (eg oxides, nitrides, carbides, borides) are more finely and uniformly distributed in component I than in conventionally prepared powders. This in turn results in an increase in sintering activity compared to the same type of phases incorporated separately. This improves the sinterability of the metal powder mixture according to the invention. Such powders using finely dispersed intercalation can be obtained, in particular, by the correct injection of oxygen during the milling process, allowing the formation of very finely dispersed oxides. Special use of milling aids may also be possible which are suitable for ODS particles and undergo mechanical homogenization and dispersion during the milling process.

The metal powder mixtures according to the invention are suitable for use in all powder metallurgy molding processes. The powder metallurgy forming process according to the invention is particularly suitable for pressing, sintering, slip casting, sheet molding, wet spraying, powder rolling (cold, hot or hot rolling), hot forming and hot working together with green processing, hot spraying and weld welding. Isotropic Pressing (HIP), Sintering HIP, Powder Loading Sintering, Cold Isostatic Pressing (CIP).

The use of metal powders in the molding process of powder metallurgy results in significant differences in processing, physical and material properties, and the chemical composition is comparable to that of conventional metal powders or to produce molded articles having the same but improved properties. To help. The presence of component II allows for accurate "tuning" of component properties such as high temperature strength, strength, toughness, wear resistance, oxidation resistance or porosity.

Pure, thermal spray powders can also be used as component repair solutions. The use of purely agglomerated / sintered powders according to International Application No. PCT / EP / 2004/00736, which is still undisclosed as thermal spray powders, will result in a characteristic coating of these components with a surface layer having better wear and corrosion properties than the base material. To help. This feature arises as a result of the very finely distributed ceramic intercalation (oxide of the element compatible with oxygen) in the alloy matrix resulting from mechanical loading during the preparation of the powder according to PCT / EP / 2004/00736. .

Component I is a metal, alloy, and composite powder that can be obtained according to a two step process in which the base powder is first transformed into flake shaped particles and then ground in the presence of a milling aid. In particular, component I, based on ASTM C 1070-01, has a mean particle size D50 of 75 μm or less, preferably 25 μm or less, as measured using a Microtrac® X100 particle size analyzer, and a base powder having a large average particle size. Particles of the base powder are treated in the deformation step with flake shaped particles having a particle size to particle thickness ratio of 10: 1 to 10000: 1 and these flake shaped particles are subjected to further processing steps in the presence of a milling aid. A metal, alloy or composite powder obtainable by a process that is exposed to grinding.

Microtrac® X100 particle size analyzer is commercially available from Honeywell, USA.

In order to measure the ratio of particle diameter to particle thickness, the particle diameter and the particle thickness are measured by a photographic optical microscope. To achieve this object, the flake shaped powder particles are first mixed with a viscous transparent epoxy resin in a ratio of 2 parts by volume of resin to 1 part by volume of flakes. The bubbles incorporated in the mixing are then removed by degassing the mixture. The bubble-free mixture is then injected into a flat substrate and rolled into a wide sheet using a roller. In this way, the flake shaped particles are preferably aligned themselves in the flow field between the roller and the substrate. Preferred layers align averagely parallel to the normal of the surface of the substrate where the normals of the surface of the flakes are flat, that is to say the flakes are arranged flat on the substrate in the layer on average. After curing, the sample of the appropriate dimensions becomes an epoxy resin sheet placed on the substrate. Such samples are considered using a microscope perpendicular to and parallel to the substrate. Using a microscope with a graduated lens and taking into account proper particle orientation at least 50 particles are measured and an average value is calculated from the measurements. This average value represents the particle thickness of the flake shaped particles. Particle thickness is measured on a vertical cross section through the substrate and the sample to be analyzed using a microscope with a graduated lens used to measure the particle diameter. Care should be taken to only measure particles that are placed as parallel as possible to the substrate. Since the particles are coated on all sides in a transparent resin, it is not difficult to select properly oriented particles and reliably assign the limits of the particles to be evaluated. Once more, at least 50 particles are measured and an average value is calculated from the measurements. This average value represents the particle size of the flake shaped particles. The ratio of particle diameter to particle thickness can be calculated from previously measured dimensions.

Particularly ductile metals, alloys or composite powders can be produced by this process. Soft metals, alloys or composite powders should be understood to mean those powders that undergo plastic stretching or deformation before significant material damage (brittle material, fracture of material) occurs when mechanical load is applied to the break point. . This plastic material change depends on the material and may range from 0.1 percent to several hundred percent with respect to the initial length.

The degree of ductility, that is, the ability of the material to obtain plasticity to sustain deformation under the influence of mechanical strain, can be measured or explained by mechanical tensile and / or pressure tests.

In order to measure the degree of ductility by mechanical tensile test, so-called tensile test specimens are produced from the material to be evaluated. This test piece may be, for example, a cylindrical test piece having a diameter that is reduced by about 30-50% to the center of the length over about 30-50% of the full length of the test piece. Tensile test specimens are loaded into the clamping device of an electromechanical or electrohydraulic tensile tester. Prior to the actual mechanical test, the length measuring sensor is placed in the middle of the test piece over a measuring length of about 10% of the full length of the test piece. This measuring sensor makes it possible to track the length increase over the selected measuring length while applying mechanical tensile strain. Increase the strain until the specimen breaks and evaluate the plastic part of the change in length with the aid of the stress-strain chart. Materials having a structure capable of obtaining a plastic length change of at least 0.1% will be described herein as being ductile.

Similarly, it is also possible to expose cylindrical material specimens with a diameter to thickness ratio of about 3: 1 to mechanical compressive loads in commercially available pressure testers. After applying sufficient mechanical pressure strain, the cylindrical test specimen also undergoes permanent deformation. Once the pressure is released and the specimen is removed, the ratio of diameter to thickness may appear to increase. Materials that have experienced a plastic change of at least 0.1% in this test will also be described as ductile herein.

Fine, ductile alloy powders with at least about 5% ductility are well prepared according to the above process.

The grindability of alloys or metal powders, which cannot be further milled on their own, is enhanced by the use of mechanically, mechanically and / or chemically active milling aids which are added or produced correctly in the milling process. In the basic concept of this approach, the chemical "target composition" of the powder thus produced should not be altered as a whole or should be influenced to improve processing properties such as sintering properties or flowability.

The process is suitable for producing a variety of fine metals, alloys or composite powders with an average particle diameter D50 of 75 μm or less, preferably 25 μm or less.

The resulting metals, alloys and composite powders are typically characterized by a small average particle diameter D50. The average particle diameter is preferably 15 µm or less when measured according to ASTM C 1070-01 (Measurement apparatus: Microtrac® X 100). To improve manufacturing properties that tend to make fine alloy powders poor (some material thickness is a porous structure that may be more resistant to oxidation / corrosion in the sintered state), while maintaining improved processing properties (pressing, sintering) in general It is also possible to set the D50 value (25 to 300 μm) significantly higher than that attempted.

As the base powder, for example, a powder already having the composition of the desired metal, alloy or composite powder can be used. However, it is also possible to use a mixture of various base powders in a process that produces the desired composition only through the selection of an appropriate mixing ratio. In addition, the composition of the resulting metal, alloy or composite powder can also be influenced by the choice of milling aid since the milling aid remains in the product.

Spherical or irregular shaped particles and average particle diameters of more than 75 μm, in particular more than 25 μm, preferably 30 to 2000 μm, or 30 to 1000 μm, or 75 μm to 2000 μm as measured according to ASTM C 1070-01 or It is preferable to use a powder having a thickness of 75 µm to 1000 µm or 30 µm to 150 µm as the base powder.

The required base powder can be obtained, for example, by atomization of the metal melt and subsequent classification or sieving as necessary. The base powder is first exposed to the deformation step. This deformation step can be carried out in known apparatus such as rolling mills, Hamtag tags, high energy mills or attritors or stirred ball mills. By finally selecting the appropriate process variables the individual particles are deformed by the effect of mechanical strain sufficient to obtain plastic deformation of the material or powder particles, which finally take the form of flakes, the thickness of which is preferably between 1 and 20 μm. It becomes This can be done, for example, by loading it once in a roller or hammer mill, by loading it several times in a "small" deformation step, or by, for example, impact milling of a Haytag mill or Simoloyer® or for example in an ultra-mill or ball mill. And wear milling. Applying a high load to the material during this deformation can cause structural changes and / or brittleness in the material, which can be used in subsequent steps to crush the material.

Known melt metallurgical rapid solidification processes can also be used to make ribbons or flakes. These are suitable for the grinding process as described later, similarly to the mechanically produced flakes.

The apparatus, milling media and other milling conditions under which the deformation step is carried out ensure that impurities resulting from wear and / or reaction with oxygen or nitrogen are kept at the lowest possible level and are within critical levels or materials for the application of the product. It is desirable to select to fall within the applicable standard.

This can be achieved, for example, by appropriate selection of materials for milling vessels and milling media, and / or the use of oxidation and nitriding inhibiting gases and / or the addition of protective solvents during the transformation step.

In a particular process embodiment, the flake shaped particles are produced directly from the melt by a rapid solidification step such as so-called melt spinning, cooling on or between one or more preferably cooled one or more rollers. Flakes are formed immediately.

The flake shaped particles formed in the deformation stage are subjected to the grinding operation. This first changes the ratio of particle size to particle thickness, and the original particles (particles to be obtained by agglomeration dissolution) generally have a ratio of particle size to particle thickness of from 1: 1 to 100: 1, preferably from 1: 1 to 10: Obtained in 1 state. Secondly, the desired average particle diameter of 75 mu m or less, preferably 25 mu m or less, is set without re-producing agglomerates of particles that are difficult to grind.

Grinding can be carried out, for example, in mills such as eccentric vibratory mills, as well as in material bed roller mills, injectors or similar devices which affect the destruction of materials in the flakes by different movements and load speeds.

Grinding is carried out in the presence of milling aids. Liquid milling aids, waxes and / or brittle powders can be added, for example, as milling aids. This milling aid may serve a mechanical, chemical or mechanochemical function.

The milling aid may be, for example, paraffin oil, paraffin wax, metal powder, alloy powder, metal sulfide, metal salt, organic acid salt and / or powder of hard material.

The brittle powder or phase acts as a mechanical milling aid and can be used, for example, in the form of alloys, elements, hard materials, carbides, silicides, oxides, borides, nitrides or basic powders. Pre-milled elements and / or alloys are used, for example, with base powders that are not easily milled to produce a powder product having the desired composition.

Powders composed of binary, tertiary and / or more compositions of elements A, B, C and / or D present in the base alloy to be used are preferably used as brittle powders, where A, B, C, D are Has a given meaning.

Liquid and / or easily modified milling aids such as waxes may also be used. Examples of such adjuvants include hydrocarbons such as hexane, alcohols, amines or aqueous media. These may be desirable compounds that are needed for subsequent steps in the further process and / or that can be easily removed after grinding.

It is also possible to use certain organic compounds known as pigment products and used to stabilize a single flake which is not agglomerated in a liquid environment.

In a particular embodiment, milling aids are used to initiate accurate chemical reactions with the base powder to augment milling and / or to set a particular chemical composition of the product. These adjuvants may be degradable chemical compounds that will require only one or more components to set the desired composition, and at least one component or element may be removed in bulk by a thermal process.

For example, hydrides, oxides, sulfides, salts, which are at least partially removed from the milled material in the steps of the subsequent process and / or powder metallurgical processing of the product powder and chemically supplement the powder composition in the desired manner with the remaining residues. And reducing or decomposable compounds such as sugars.

It is also possible to prepare the aid in situ during grinding, rather than adding the milling aid separately. This can be done, for example, by producing a milling aid by the addition of a reaction gas which reacts with the base powder under the grinding conditions to form a brittle phase. Hydrogen is preferred as the reaction gas.

For example, brittle phases produced during treatment with the reactant gases by the formation of hydrides and / or oxides are generally again subjected to corresponding process steps during processing of the fine metals, alloys or composite powders once grinding is complete or obtained. Can be removed.

When using abrasive aids that cannot or cannot be removed from the manufactured metal, alloy or composite powder, these aids have the desired effect that the residual components have on the properties of the material, such as improved mechanical properties, reduced corrosion incidence, increased hardness. It is preferred to be selected to have abrasion action or an improvement in friction and slip characteristics. An example of this is the use of hard materials, the proportion of which increases with the alloying components in a subsequent step so that the hard materials can be further processed into a hard metal or a hard metal alloy composite material.

After the deformation step and milling, the primary particles of the prepared metal, alloy or composite powder are usually 25 μm, preferably less than 75 μm, in particular 25, as measured using Microtrac® X100 according to ASTM C 1070-01. Μm or less has a preferable average particle diameter D50.

Despite the use of milling aids, the coarse secondary particles (lumps) having a particle size significantly larger than the desired maximum average particle diameter of 25 μm are the desired formation of fine primary particles as a result of known interactions between the ultrafine particles. It can be formed in addition to.

For this reason, the product to be produced does not allow condensation or require (coarse) condensation since the flocculation disintegration step is preferably followed by grinding, where condensation is disintegrated and primary particles are released. Agglomeration disaggregation can be effected, for example, by applying shear forces in the form of mechanical and / or thermal stresses and / or by removing the interlayer pre-inserted between the primary particles in the process. The particular deagglomeration method to be used depends on the degree of condensation, the intended use and the rate of oxidation of the ultrafine powders and acceptable impurities in the product.

Agglomeration disintegration may occur by mechanical methods, for example by treatment in gas countercurrent mills, sieving, fractionation or in an attritor, kneader, or rotor-stator disperser. For example, voltage fields generated from heat treatment, such as decomposition or conversion of premixed interlayers between primary particles by sonication, low temperature or high temperature treatment, or chemical substitution of mixed or intentionally prepared phases, may also be used.

Aggregation dissolution is preferably carried out in the presence of one or more liquids, dispersion aids and / or binders. In this way, slips, pastes, dough compositions or suspensions with a solids content of 1 to 95% by weight can be obtained. The solids content of 30 to 95% by weight can be processed directly by processes according to known powder techniques such as injection molding, sheet molding, coating, hot casting and then converted to the final product in the appropriate drying, debonding and sintering steps. .

Especially for the coagulation dissolution of oxygen sensitive powders, gas countercurrent mills operated under inert gas such as argon or nitrogen are preferably used.

The metals, alloys or composite powders produced have a number of special features compared to conventional powders produced by, for example, atomization while having the same average particle diameter and the same chemical composition.

The metal powder of component I has, for example, good sintering properties. At low sintering temperatures, substantially the same sintering density can be achieved as with powders prepared by atomization. At the same sintering temperature, higher sintering densities can be achieved for the metal parts of the compacted body based on powder compacts of the same compression density. This increased sintering activity is, for example, the fact that during the sintering process the shrinkage of the powder according to the invention is usually within the main shrinkage maximum than that of the powder produced, and / or the temperature at which the shrinkage peak occurs (standardized) It can be seen from the fact that using PZD powder is lower. The body compressed in the minor axis can make different shrinkage paths parallel and perpendicular to the compression direction. In this case, the shrink curve is mathematically determined by the addition of the amount of shrinkage at the relative temperature. Here, shrinkage in the compression direction occupies one third of the contraction curve, and contraction in the direction perpendicular to the compression direction occupies two thirds of the contraction curve.

The metal powders of component I are measured using dilatometers in accordance with DIN 51045-1 within the temperature of the first maximum shrinkage, so that the shrinkage of the metals, alloys or composite powders of the same average particle diameter D50 with the same chemical composition produced by atomization It is such a metal powder that is at least 1.05 times shrinkage and that the powder under investigation shrinks to a compressive density of 50% of theoretical density before measuring shrinkage.

The metal powders of component I are also characterized as a result of special particle morphology with a rough particle surface by a relatively better compression function and as a result of a relatively wide particle size distribution by a highly compressed density. This indicates that the densities of atomized powders using different identical manufacturing conditions have lower refractive intensities (so-called holding strengths) than the densities of PZD powders of the same chemical composition and of the same average particle size D50.

The sintering properties of the powders of component I can also be specifically influenced by the choice of milling aids. Thus, one or more alloys already form a liquid phase during heating due to their low melting point compared to the base alloy and improve the rearrangement and material diffusion of the particles, furthermore the sintering and shrinking function, so that the high sintering density is at the same or at the same sintering temperature It can be used as a milling aid that allows the density to be achieved at lower temperatures than the reference powder. Chemically degradable compounds may also be used, the decomposition products of which, together with the base material, produce liquid phase (s) with high diffusion coefficients that are advantageous for compression molding.

Conventional metal powder (MLV) in powder metallurgy applications is a powder having a substantially spherical particle shape as shown by way of example in FIG. 1 of International Application No. PCT / EP / 2004/00736. Such metal powders may be elemental powders or alloy powders. Such powders are known to those skilled in the art and are commercially available. Numerous chemical and metallurgical processes are known for this manufacture. When producing fine powders, known processes often begin by dissolving the metal or alloy. Mechanically rough and fine grinding of metals or alloys is also frequently used for the production of "traditional powders", but produces powder particles having a non-spherical shape. It constitutes a very simple and efficient method of powder generation as long as it functions in principle ('Powder metallurgy-processing and materials' by W. Schatt, K.-P. Wieters, European Powder Metallurgy Association (EPMA), 1997, 5-10). The atomization method is also crucial for establishing the shape of the particles.

When the melt is disintegrated by atomization, the powder particles are formed directly by solidification from the resulting melt droplets. Depending on the cooling method (treatment with air, inert gas, water), used process variables such as nozzle geometry, gas velocity, gas temperature or nozzle material, melting point and freezing point, solidification action, viscosity, chemical composition and process There are material parameters of the melt, such as reactivity with the media, numerous possibilities, and process constraints ('Powder metallurgy-processing and materials' by W. Schatt, K.-P. Wieters, European Powder Metallurgy). (EPMA), 1997, 10-23).

Since the manufacture of powders by atomization is important in special industries and economics, various atomization concepts have been established. For example, depending on the required powder properties, such as particle size, particle size distribution, particle morphology, impurities, etc., and the properties of the melt to be atomized, such as melting point or reactivity, and the allowable cost, the desired process is selected. Nevertheless, according to industrial and economic aspects, powders with a certain characteristic profile (particle size distribution, impurity content, yield of 'target gain', morphology, sintering activity, etc.) are often limited to obtain at a reasonable cost ( See W. Schatt, K.-P. Wieters 'Powder metallurgy-processing and materials', European Powder Metallurgy Association (EPMA), 1997, 10-23).

The manufacture of conventional metal powders for application to powder metallurgy by atomization has all the disadvantages mentioned above, which requires the use of large amounts of energy and atomizing gases, which will dramatically increase the cost of the process. In particular, it is uneconomical to produce fine powders with high melting point alloys with melting points above 1400 ° C., because on the one hand high melting points require high energy inputs to produce the melt and on the other hand the desired particles. This is because gas consumption increases rapidly as the size decreases. In addition, sometimes difficulties exist when at least one alloying element has a high oxygen affinity. The use of specially developed nozzles yields a cost-related advantage in the production of fine alloy powders.

Additionally, preparing conventional metal powders for application to powder metallurgy by atomization is called "melt spinning," which injects melt on a cooled roller and produces a thin, generally easily crushable ribbon. Another single-step melt metallurgical process is also frequently used, such as "crucible melt extraction," which extracts particles and fibers by probing a cooled, profiled rapid spinning roller into the metal melt.

A further important variant with respect to the preparation of conventional metal powders for application in powder metallurgy is the chemical route through the reduction of metal oxides or metal salts. However, alloy powders cannot be prepared in this way (see 'Powder metallurgy-processing and materials', W. Schatt, K.-P. Wieters, European Powder Metallurgy Association (EPMA), 1997, 23-30).

Ultrafine particles with a particle size of less than 1 micrometer can also be produced by combining the evaporation and condensation processes of metals and alloys and by gas phase reduction (W. Schatt, K.-P. Wieters' Powder Metallurgy -Processing and Materials', see European Powder Metallurgy Association (EPMA), 1997, 39-41). However, this process is very expensive industrially.

If the melt is cooled to large volumes / blocks, it will require mechanical process steps for coarse, fine, ultrafine grinding to produce metal or alloy powders that can be processed by powder metallurgy. Mechanical powder production is described by W. Schatt, K.-P. Powdered metallurgy-processing and materials in the Wieters book, European Powder Metallurgy Association (EPMA), 1997, 5-47.

As the oldest method of particle size setting, mechanical grinding in mills is particularly advantageous from an industrial point of view because it can be applied to many materials at low cost. However, this method places special demands on the charging material, for example with regard to the size of the fragments and the brittleness of the material. In addition, grinding cannot last for an indefinite period of time. Rather, a milling equilibrium is formed even when the milling process starts with finer powder. Conventional milling processes are improved when the physical limit of the grinding capacity is reached for a particular milling material, for example some phenomenon such as brittleness at low temperatures, or the effect of the milling aid improves the milling function or grinding capacity. Conventional metal powders for application in powder metallurgy can be obtained by the process as described above.

Independently of each other, components I and II may be chemically identical or different and may be elemental powders, alloy powders or mixtures thereof.

The metal powders of components I and II may have the composition of formula I.

hA- iB-jC-kD (formula Ⅰ)

here,

A represents one or more elements of the elements Fe, Co, and Ni.

B refers to one or more elements of the elements V, Nb, Ta, Cr, Mo, W, Mn, Re, Ti, Si, Ge, Be, Au, Ag, Ru, Rh, Pd, Os, Ir, Pt.

C refers to one or more elements of the elements Mg, Al, Sn, Cu, Zn.

D is one or more of the elements Zr, Hf, Mg, Ca rare earth metals (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) Point to an element.

And h, i, j, k are given by weight fraction, where

h, i, j, k are each independently 0 to 100% by weight,

The sum of h, i, j and k is 100% by weight.

According to a further embodiment of the invention,

A represents one or more elements of the elements Fe, Co, and Ni.

B indicates at least one element of the elements V, Cr, Mo, W, Ti.

C refers to one or more elements of the elements Mg and Al.

D represents one or more elements of the elements Zr, Hf, Y, La.

In Formula I, h is 50 to 80% or 60 to 80%, i is 15 to 40% or 18 to 40%, j is 0 to 15% or 5 to 10%, k is 0 to 5 weight% or 0-2 weight%, respectively.

In another embodiment of the invention, component I and component II are elemental powders or binary alloy powders so that shaped articles obtainable from metal powder mixtures according to the invention have correspondingly more complex compositions. For example, in this embodiment of the present invention, a molded article consisting of an employee alloy can be obtained through the use of binary alloys for component I and component II.

According to another embodiment of the present invention, components I and II are multipart alloy powders such as binary or quaternary alloy powders so that shaped articles obtainable from metal powder mixtures according to the invention have a correspondingly more complex composition. Components I and II can thus be composed of alloys comprising two to five different metals independently of one another, thus making it possible to produce more complex alloys. For example, in this embodiment of the present invention, a molded article consisting of an alloy comprising six metals can be obtained by using a binary alloy for component I and an employee alloy for component II.

According to another embodiment of the invention, the composition of components I and II of the metal powder mixture and the shaped articles obtained therefrom differ from each other.

In another embodiment of the invention, the shaped article obtainable by subjecting the metal powder mixture according to the invention to a powder metallurgy molding process has a composition of formula (I).

According to another embodiment of the invention, the molded article, component I and / or component II is substantially Fe20Cr10Al0.3Y, Fe22Cr7V0.3Y, FeCrVY, Ni57Mo17Cr16FeWMn, Ni17Mo15Cr6Fe5WlCo, Ni20Cr16Co2.5Ti1.5Al and Ni53Cr20Co18Ti2.5Al1.5Fe1.5 It is composed of an alloy selected from the group containing.

In another embodiment of the present invention, component I and / or component II may even be a powder mixture of different elemental powders or alloy powders. In this case, for example, a molded article containing six metals as an alloy component can be obtained by mixing component I, which is a binary alloy, respectively, component IIa and component IIb, which are binary alloys, and subjecting them to a powder metallurgical molding process.

The amount of component II in the metal powder mixture depends on the form and extent of the effect intended to be obtained and on the desired chemical composition of the shaped product obtained when the metal powder mixture is subjected to a powder metallurgical molding process. However, when component I and component II are identical, the chemical composition of the molded article is established in advance. However, if the components I and II are different, they depend on the type, composition and content of components I and II of the resulting molded article, which must be controlled accordingly. According to the invention, the molded article can be made of a high alloy metal material using a process that was previously unsuitable for manufacturing. Those skilled in the art are in principle accustomed to boosting effectiveness, so the optimum mixture for the individual application can be established with a few attempts. Conventional metal powders are generally used in the ratio of component I to component II of 1: 100 to 100: 1 or 1:10 to 10: 1 or 1: 2 to 2: 1 or 1: 1.

The present invention can be used to produce high alloy materials. Possible procedures will be described in detail below. The complex alloy component for the metal powder mixture will generally be described as follows, the sum of the factors a, b, c constitute 100% by weight, and the symbols aBMP-bLEM-cDOT-dMHM-eFUZ are used as follows. In other words,

BMP (Base Metal Powder): Fe, Ni, Co

LEM (alloy element): Cr, Al, Ti, Mo, W, Nb, Ta, V, ...

DOT (Dopant): SE (rare earth metal), Zr, Hf, Mg, Ca

MHM (milling aid) paraffins, hydrocarbons, brittle intermediate metal phases, other brittle phases (ceramic, hard materials)

Functional Additives (FUZ) Ceramics, Hydrocarbons, Sulfide

Factors d and e represent the amount of milling aid or functional additive that can be additionally obtained.

In one embodiment of the invention the alloy composition is still used. The composition of the metal powder mixture is as follows. In other words,

Component I: a ₁ BMP-b ₁ LEM-c ₁ DOT-d ₁ MHM

Component II: a ₂ BMP-b ₂ LEM-c ₂ DOT

Component III:-e ₃ FUZ

Where e ₃ = 0

In this case, the alloy constituting the molded product obtained from the metal powder mixture is made as follows.

(a ₁₊ a ₂ ) BMP-(b ₁₊ b ₂ ) LEM-(c ₁₊ c ₂ ) DOT

(No milling aid)

In this case a ₁ = a ₂ , b ₁ = b ₂ , and c ₁ = c ₂ , which means that component I is a mixture of the same alloy, which is a PZD powder. The (organic) milling aid (MHM) is not mentioned because it can be completely removed during processing and does not alter the alloy. The fractions of component I and component II may vary between 100% component I and 0% component II and 1% component I and 99% component II depending on the requirements of the processing or functional properties.

In another embodiment of the present invention, the alloy composition varies with the fraction of components I and II. The metal powder mixture is composed as follows. In other words,

Component I: a ₁ BMP-b ₁ LEM-d ₁ MHM

Component II: a ₂ BMP-c ₂ DOT

Component III: not present

In this case, the alloy constituting the molded product obtained from the metal powder mixture is made as follows.

(a ₁₊ a ₂ ) BMP-(b ₁ ) LEM-(c ₁ ) DOT

(No milling aid)

In this case a ₁ ? A ₂ , b ₁ ? B ₂ , and c ₁ ? C ₂ , which means that two alloys are present. Component I consists only of base metal powder (BMP) and alloying elements (LEM), and Component II is a compound to be added which is characterized by special metallurgical properties (eg low melting point) and / or mechanical properties (eg brittle, easily crushable). Dopants present in a concentrated form. In this way, powder technical advantages (sintering with liquid phase) can be used to form the desired final alloy. Here the dopant is implanted in the form of a masterbatch, which may be advantageous depending on the type and composition of the alloy. The (organic) milling aids are not mentioned because they are completely removed during processing and do not alter the alloy. The volume fraction of component I and component II is selected by a person skilled in the art according to the target composition.

In a further embodiment of the invention, the alloy composition changes with the fraction of components I, IIa, and IIb. The metal powder mixture is composed as follows.

Component I: a ₁ BMP-b ₁ LEM-d ₁ MHM

Component IIa: a ₂ BMP-b ₂ LEM-c ₂ DOT

Component IIb: a ₃ BMP

In this case, the alloy constituting the molded product obtained from the metal powder mixture is made as follows.

(a ₁₊ a ₂₊ a ₃ ) BMP-(b ₁ ) LEM-(c ₁ ) DOT

(No milling aid)

In this case a ₁ ? A ₂ ? A ₃ , b ₁ ? B ₂ , and c ₁ ? C ₂ , which means that there are two alloys and the base metal powder. Component I consists only of base metal powder (BMP) and alloy element (LEM), and component IIa is concentrated form with base metal and / or alloy element as dopant for advantageous use of special metallurgical and mechanical properties. It includes dopants present. Component IIb comprises a base metal that can be produced simply and cost-effectively, which forms the entire alloy when added to components I, IIa, IIb. In this way, in addition to the powder technical advantages of the foregoing embodiments, technical and economic advantages can also be used. The (organic) milling aids are not mentioned because they are completely removed during processing and do not alter the alloy.

In a further embodiment of the invention, the alloy composition varies with the fraction of components I and II. Brittle alloys are advantageously used as milling aids. The metal powder mixture is composed as follows. In other words,

Component I: a ₁ BMP-b ₁ LEM-d ₁ MHM = (c ₂ BMP-c ₂ DOT)

Component II: a ₃ BMP

Component III: -e ₃ FUZ = paraffin

In this case, the alloy constituting the molded product obtained from the metal powder mixture is made as follows.

(a _{1 +} a _{2 +} a ₃ ) BMP (b ₁ ) LEM-(c ₂ ) DOT

(No milling aid)

In this case a ₁ ? A ₂ ? A ₃ , which means that the alloy and the base metal powder are present. Component I consists only of base metal powder (BMP) and alloying elements (LEM). A particularly brittle composition consisting of BMP and DOT is used as milling aid. Paraffin in powder form is mixed as component III. Using component II, the composition can be corrected in this case using a base metal powder. In this way, the powder technical advantages of the alloy (a ₂ BMP-c ₂ DOT) can be used. Milling aids are not listed individually because they disappear into the alloys that make up the molded product.

In another embodiment of the present invention, the composition varies depending on the fraction of components I and II. The brittle alloy a ₂ BMP-c ₂ DOT is used as milling aid and the organic components and ceramic particles are used as functional additives (FUZZ). The metal powder mixture is composed as follows. In other words,

Component I: a ₁ BMP-b ₁ LEM-d ₁ MHM = (a ₂ BMP-c ₂ DOT)

Component II: a ₃ BMP

Component III: -e ₃ FUZ = PVA, ceramic

In this case, the alloy constituting the molded product obtained from the metal powder mixture is made as follows.

(a ₁₊ a ₂₊ a ₃ ) BMP =-(b ₁ ) LEM-(c ₂ ) DOT

(No milling aid)

In this case a ₁ ? A ₂ ? A ₃ , which means that the alloy and the base metal powder are present. Component I consists of a base metal powder and an alloying element. A brittle composition composed of a base metal and a dopant is used as milling aid. Correction can be made to the composition using a base metal powder. Component III comprises ceramic particles and PVA (polyvinyl alcohol) which is advantageous for further processing, for example by spray drying. Such mixtures can be treated, for example, with a thermal spray of powder. In this way, the powder technical advantages of the alloy (a ₂ BMP-c ₂ DOT) and the action of functional additives (hardness, wear resistance) can be exploited when the powder is processed, for example by thermal spraying.

The metal powder may comprise a functional adhesive as component III. Functional additives are additives that increase impact strength or wear resistance, such as ultrahard powders, additives that facilitate processing of the molded body by reducing the brittleness of the molded body and / or increasing its strength, or controlling the pore structure or surface properties. The additive, which acts as a template in order to impart characteristic properties to the articles molded from PZD powders.

Functional additives are to be understood as meaning those homogeneously mixed additives which are mostly or completely present in the product, the molded product or which are mostly or completely removed from the finished product.

Among these, the primary products are, for example, mechanical properties such as hardness, strength, damping or impact strength, or chemical properties such as oxidation / corrosion, or tribology, haptics, electrical and magnetic conductivity, modulus of elasticity, It is a functional additive which controls functional characteristics, such as electrical dissipation property, magnetostrictive property, and electrostrictive property by these fractions and basic characteristics.

Complex mechanical, chemical and functional features include, for example, carbides, borides, nitrides, oxides, silicides, hydrides, diamonds, in particular carbides, borides and nitrides of elements of groups 4, 5 and 6 of the periodicity, 4, Oxides of groups 5 and 6, and oxides of aluminum and rare earth metals, aluminum, boron, cobalt, nickel, iron, molybdenum, tungsten, manganese, zirconium silicides, tantalum, nionium, titanium, magnesium and tungsten Chemical particles or hard materials such as hydrides; Slip additives with lubricating properties such as graphite, sulfides, oxides, especially molybdenum sulfide, zinc sulfide, tin sulfide (SnS, SnS ₂ ), copper sulfide and the like, and especially magnetic or electrical properties on rare earth-cobalt or rare earth iron bases It can be brought about by incorporation of various phases / components, such as an intermetallic compound.

Due to this meaning, the coating of ultrahard powders with PZD powders can also be made using metal powder mixtures. This can be advantageously achieved by fluid bed granulation.

For example, coarse (50-100 μm) hard particle particles of BN and TiB ₂ may be used as feedstock for fluid bed granulation and may be provided as a corrosion resistant coating. Therefore, it can be newly applied in the fields where high corrosion and wear under mechanical load occur. After coating, the mass is separated, sintered in an inert atmosphere and coated by thermal spraying.

In the second case, in other words, when using a functional additive that is mostly or completely removed from the product, the additive used is a so-called place-holder that is removed by a suitable chemical or thermal process to function as a template. These may be hydrocarbons or plastics. Suitable hydrocarbons are low molecular wax polyolefins such as low molecular polyethylene or polypropylene, and long chain hydrocarbons such as saturated, fully or partially unsaturated hydrocarbons, waxes and paraffins having 10 to 50 carbon atoms, or 20 to 40 carbon atoms. Suitable plastics have particularly low ceiling temperatures, in particular ceiling temperatures below 400 ° C, or below 300 ° C or below 200 ° C. Above the ceiling temperature, plastics become thermodynamically unstable and tend to decompose into monomers (depolymerization). Suitable plastics are, for example, polyurethanes, polyacetals, polyacrylates, in particular polymethyl, methacrylate, or polystyrene. In a further embodiment of the invention, plastics are preferably used in the form of expandable particles, such as expandable polystyrene beads used as preliminary materials in packaging manufacture or as intermediate products. Inorganic compounds that tend to sublime are also, for example, some oxides of refractory metals, in particular oxides of rhenium and molybdenum, also hydrides (Ti hydrides, Mg hydrides, Ta hydrides), organic (metal stearates) Or as a partially or fully degradable compound, such as an inorganic salt, which can act as a position holder.

Due to the addition of such functional additives, the metal powder mixtures according to the invention comprising these functional additives as position holders are exposed to a powder metallurgy molding process, thereby providing a high density of components (90-100% of the theoretical density), low porosity (theoretical). Density: 70 to 90%), high porosity (theoretical density: 5 to 70%) can be prepared.

The amount of functional additive depends in principle on the form and extent of the effect to be obtained, which is familiar to those skilled in the art, so an optimum mixture can be established with a few attempts. When using such compounds, care must be taken to ensure that the compound used as the position holder / template is present in the metal powder mixture in the form of a structure suitable for this purpose, ie in the form of granular powder, spherical particles or similar particles.

In general, functional additives are used in fractions of component I to component II of 1: 100 to 100: 1 or 1:10 to 10: 1 or 1: 2 to 2: 1 or 1: 1. If the functional additive is a hard material such as tungsten carbide, boron nitride or titanium nitride, they may be 3: 1 to 1: 100, or 1: 1 to 1:10, or 1: 2 to 1: 7, or 1: 3 to It is advantageously used in an amount of 1: 6.3.

In another embodiment of the present invention, the functional additive is glass in an amount of 3: 1 to 1: 100, or 1: 1 to 1:10, or 1: 2 to 1: 7 or 1: 3 to 1: 6.3. Is used.

According to another embodiment of the invention, the ratio of component I to component III is 3: 1 to 1: 100, or 1: 1 to 1:10, or 1: 2 to 1: 7, or 1: 3 to 1: If 6.3, the metal powder mixture is a mixture of component I and component II and / or component III.

In another embodiment of the present invention, when the hard material is present in component III, the ratio of component I to component III is 3: 1 to 1: 100, or 1: 1 to 1:10, or 1: 2 to 1: 7 Or 1: 3 to 1: 6.3, the metal powder mixture is a mixture of component I and component II and / or component III.

In another embodiment of the present invention, when tungsten carbide is present in component III, the ratio of component I to component III is 3: 1 to 1: 100, or 1: 1 to 1:10, or 1: 2 to 1: If 7, or 1: 3 to 1: 6.3, the metal powder mixture is a mixture of component I and component II and / or component III.

Still other additives will improve the processing properties, especially the compressive properties, lump strength or redispersibility. These include waxes such as polyethylene waxes or oxidized polyethylene waxes, montonic acid esters, oleic acid esters, linoleic acid or linoleic acid esters or ester waxes such as mixtures thereof, paraffins, plastics such as resins such as rosin, montanic acid, oleic acid, linoleic acid or linolenic acid. Metal salts, such as metal stearates and metals such as zinc stearate and metals of palmitic acid, in particular alkali metals and alkaline earth metals such as stearic acid and palmitic acid, such as magnesium stearate, sodium palmite, calcium stearate Long chain organic acid salts or slip agents. These are materials typical for powder processing (pressing, MIM, sheet molding, slip casting) and known to those skilled in the art. Shrinkage of the powder to be analyzed can be carried out by adding conventional auxiliaries to assist pressing, such as, for example, paraffin wax or other waxes or salts of organic acids such as zinc stearate. Suitable additives are described in W. Schatt, K.-P. This is further described in the Witers book 'Powder metallurgy-processing and materials', European Powder Metallurgy Association (EPMA), 1997, 49-51.

The following examples serve to explain in more detail the present invention. These examples are provided for the purpose of understanding the present invention and should not be construed as limiting them.

FIG. 1 is a diagram showing an alternative relationship between powder grades VSP-711 and KON-711 with varying amounts and holding strength of pressing aids.

2 is a photograph showing test pieces VSP-711 and KON-711.

Figure 3 is a photograph showing a test piece for flat tension made by water jet cutting.

Figure 4 is a chart showing the measurement curve of the tensile specimen provided to compare the strength at room temperature.

5 is a photograph showing the porous structure of a test piece made of KON-711 and VSP-711.

FIG. 6 is a photograph showing the coating results when using a rudimentary base powder to be granulated.

7 is a table showing the measurement results of test pieces prepared from the powder of Table 6.

Yes

The average particle diameter D50 given in the examples below was measured using Microtrac® X100 from Honeywell, USA according to ASTM C 1070-01.

Example 1

Argon atomized alloy melt of Nimonic® 90 type with composition Ni20Cr16Co2.5Ti1.5Al was used as the base powder. The obtained alloy powder was sieved between 53 and 25 mu m. The density was about 8.2 g / cm ³ . The particles of the base powder were mostly spherical.

The original spherical particles became flake shaped because the base powder was exposed to strain grinding in a vertical stirred ball mill (Netzsch Feinmahltechnik; type: PR 1S). The details of the variables used are as follows. In other words,

. Grinding container volume: 5 liters

. Speed: 400rpm

. Ambient speed: 2.5m / s

. Ball charge: 80% by volume (bulk volume of balls)

. Grinding vessel material: 100Cr6 (DIN 1.3505: about 1.5% Cr by weight,

About 1 weight% C, about 0.3 weight% Si, about 0.4 weight% Mn, <0.3 weight% Ni, <0.3 weight% Cu, balance Fe)

. Ball Material: Hard Metal (WC-10Co)

. Ball diameter: approx. 6 mm (total mass: 25 kg)

. Powder weight: 500g

. Processing duration: 2 hours

. Solvent: Ethanol (about 2 liters)

This step is followed by milling. for teeth The so-called eccentric vibration mill (Siebtechnik GmbH, ESM 324) was used with the following process variables.

. Grinding vessel volume: operated as a 5 liter satellite (20 cm diameter, approx. 16 cm long)

. Ball charge: 80% by volume (bulk volume of balls)

. Grinding vessel material: 100Cr6 (DIN 1.3505: about 1.5% Cr by weight,

About 1 weight% C, about 0.3 weight% Si, about 0.4 weight% Mn, <0.3 weight% Ni, <0.3 weight% Cu, balance Fe)

. Ball Material: 100Cr6

. Ball diameter: 10 mm

. Powder weight: 150g

. Grinding Aids: 2g paraffin

. Amplitude: approx. 10 mm

. Crushing atmosphere: Argon (99.998%)

After grinding for 2 hours, very fine particle masses are obtained. In the REM image of the product obtained at 1000 times, the cauliflower-like structure of agglomerates (secondary particles) can be seen, and the primary particles have a particle diameter of less than 25 μm.

Samples of primary or very fine particle agglomerates were subjected to agglomeration dissolution by sonication for 10 minutes in isopropanol in a TG 400 ultrasonic device (manufactured by Sonic Ultraschallanlagenbau GmbH) at 50% of maximum output to obtain isolated primary particles. 3 process steps were received.

The particle size distribution of the agglomerated samples was measured using Microtrac® X100 (manufactured by Honeywell / US) according to ASTM C 1070-01. The D50 value of the base powder amounted to 40 mu m and belonged to about 15 mu m as a result of the treatment.

Another third for flocculation by the treatment in a gas countercurrent mill with the sonication subsequent to isopropanol in the TG 400 ultrasonic apparatus (manufactured by Sonic Ultraschallanlagenbau GmbH) at 50% of the maximum output from the milling. Received the process step. Particle size was again measured using ASTM C 1070-01. The D50 value is now only 8.4 μm.

The mixed paraffin grinding aid may be removed during powder metallurgical further processing of the alloy powder by thermal separation and / or evaporation or may serve as a pressing aid.

The metal powder mixture according to the invention was prepared from the PZD powders obtained as described above as follows.

5 kg of Nimonic® 90 PZD powder prepared as described above (d50: 10 μm and d90: 20 μm) and 5 kg of spherical (gas atomized) Nimonic® 90 powder (d50: 10 μm and d90) : 20 μm) was added to the Eirich mixer with 233 g of pressing aid in powder form (Licowax C). The three components were mixed vigorously with each other over a 20 minute period. This powder is called VSP-711.

Similarly, 10 kg of purely atomized (conventional) powder (Nimonic® 90 powder (d50: 10 μm and d90: 20 μm)) was treated in the same manner except adding 300 g of Licowax. . This powder is called KON-711.

Both powders were processed by uniaxial pressing at a pressure of 500 MPa into a cylinder having a length of 10 mm and a diameter of 30 mm. Although the compressive density of KON-711 was set to a theoretical density of 75%, the test specimen had only a low holding strength. The specimens obtained from VSP-711 improved their strength significantly despite their low theoretical density (70%).

In order to accurately measure the body strength, a square shaped compressed body was produced at a pressing pressure of 500 MPa. 1 shows an alternative relationship between powder grades VSP-711 and KON-711 with varying amounts and strength of pressing aids. The holding strength of the compressed body produced from VSP-711 is within 2.5 MPa under the conditions described, and thus at least twice the strength of the reference sample KON-711. The compressive strength of the test piece with right angle cross section under refractive strain was measured according to DIN ISO 3995/1985. The results of these measurements are reported in Table 1.

Possession strength Paraffin Content (Pressing Aid) Holding strength in accordance with DIN ISO 3995 [MPa] % KON-711 VSP-711 0.7 nmb 0.7 2 - 1.7 3 1.2 2.5 4 2.1 -

Nmb: Test piece collapses during handling and cannot be measured

The powder protons (VSP-711 and KON-711) were compressed in a metal powder press to further test specimens with an area of 6.35 cm ² (parallel to the pressing direction) and a length of about 5 mm according to DIN ISO 3927, ie PM tensile test. Made a bar The pressure was varied in the range of 300 to 800 MPa. The density of the components increases with increasing pressure. Table 2 shows this dependence of the influence of the pressing pressure on the holding strength of the tensile test piece pressed directly from the powders [A (area in the pressing direction): 6.35 cm ² ; L (length of the test piece in the pressing direction): 4-5 mm]. It should be noted here that the given density value is related to the mixture of the metal powder and the pressing aid (3% Licowax).

Compression density Compression Density / g / cm ³ Compression Density / MPa KON-7.1 VSP-7.1 300 5.8 5.65 400 5.95 5.7 500 6.1 5.8 600 6.2 5.95 700 6.3 6 800 6.4 6.05

The PM tensile test bar was shorted in a gas stream under hydrogen at a heating rate of 2 K / min from room temperature to 600 ° C. and then sintered at a high vibration of about 10 ⁻³ mbar at a temperature of 1290 ° C. for 2 hours. Test specimens of powder type KON-711 showed damage (balance, fracture precursor) that was not seen in the compressed state after short-circuit and sintering. In contrast, the tensile specimens of the VSP-711 had a homogeneous specimen surface with no damage and little roughness. These specimens are shown in FIG. Additionally, a short circuit at room temperature from 600 ° C. at a heating rate of 2 K / min was followed by shrinking under hydrogen by hot forming (1150 ° C./2 h / 35 MPa / nitrogen) in a graphite mold. After hot forming, the temperature was reduced by about 5-15 K / min until reaching room temperature. Thus, the formed disks had density of 8.18 g / cm ³ (KON-711) and 8.14 g / cm ³ (VSP-711). Both sides of these disks (diameter: 100 mm; thickness about 5 mm) were polished and the thickness was reduced to 3.5 mm. From these, flat tensile specimens were made by water jet cutting as shown in FIG. 3, and their mechanical properties were evaluated in a tensile tester (Rm, strain on break in tensile test; Pp0.2, elongation of tensile test specimen) Mechanical strain when measured at 0.2%). The measurement curve of the tensile test is shown in FIG. 4 and allows comparison of the strength at room temperature.

The compact was compressed at 500 MPa and sintered in a drying furnace at 1300 ° C. and 1330 ° C. for 2 hours in an argon-hydrogen atmosphere (6.5 vol% H ₂ ), after which the organic pressing aid was removed to within 600 ° C. under hydrogen. The results are listed in Table 2b.

Sintering Conditions and Sintered Density  Density change at temperature rise of 30 ° C [TD] 3% PHM 1300 ℃ / 2h / ArH ₂ 3% PHM 1330 ℃ / 2h / ArH ₂ Test piece name [g / cm ³ ] [TD] KON_7.1 7.35 (90%) 7.72 (94%) 4% VSP_7.1 7.5 (91%) 7.84 (96%) 5%

Additional specificity is concentrated in the porous structure of test specimens made from KON-711 and VSP-711 shown in FIG. 5.

Example 2

Easily compressible, flowable and easily sinterable granules are produced as follows.

5 kg of Nimonic® 90 PZD powder (d50: 10 μm and d90: 20 μm) and 5 kg of spherical (gas atomized) Nimonic® 90 powder (d50: 10 μm) prepared as in Example 1 d90: 20 μm) was added to 2-3 liters of water with an organic binder (3% by weight polyvinyl alcohol, PVA) and a surface activity stabilizer. This mixture was dispersed until a stable suspension was formed. This suspension is treated by spray drying to agglomerates of spherical single particles, most of which are 1 to 150 micrometers in diameter. Heated nitrogen (gas temperature 30 ° C. to 80 ° C.) in countercurrent to dry the suspension is used as working gas. The gas mixture formed during drying is discharged through the filter into the atmosphere at the outlet of the spray dryer.

In order to improve further processing capacity and to meet health impact criteria, a 'sieve' fine content (<10 μm) and very coarse grain content (> 150 μm) are separated by sieving. This granule (-150 μm + 10 μm) has excellent flow characteristics. The granularity thus obtained is referred to as VSP-712.

Simultaneously with the preparation of this granular, elementalized (conventional) powder (10 kg) (Nimonic® 90-powder (d50: 10 mu m and d90: 20 mu m)) was granulated (-150 mu m + 10 mu m) in the same manner. ) This powder is called KON-712.

The pressing properties, the base shrinkage strength, the sintering properties and the quality (roughness) of the surface of the powder protons (VSP-712 and KON-712) were evaluated in the same manner as described in Example 1. The result is consistent with the data determined in the above example.

Example 3

Preparation of granulated granules

In each case, the compacts were prepared by cold isostatic molding (CIP) using VSP-711 and KON-711 prepared in Example 1. To achieve this goal, the granules are injected into a rubber mold, sealed with an airtight seal and then shrunk at a constant pressing pressure of 2000 bar. The shrinkage of the compressed body of KON-711 is measured at 70% TD, but the compression density of VSP-711 is about 65% TD. The CIP compacts were then broken one by one by machining (loaded on the shelf and cut into rough "chips"). In the case of the VSP-711, it can be successfully treated with grains with a large fraction (d50:> 50% with a particle size of> 100 μm). Primary powder products (particles> 100 μm (<5%)) were obtained from compacts of KON-711.

This preliminary granulation is then further processed with a sieve granulator plate. This process rounds the edges of the 'powder chip', creating a more fluid granule. After sieving, a fraction of -65 μm + 25 μm was obtained, which was a fraction of the particle size of less than 65 μm and the particle size of more than 25 μm. This granulation can be further treated with a powder metallurgy molding process. This fraction is called VSP-721 and KON-721. The total yield from the production of high density and flowable granules is 20-50% for VSP-721 and <20% for KON-721. Granular portions that do not lie in the desired grain band can be recycled in the manufacturing process for the CIP body.

Investigation of the processing properties (base strength, sintering properties) of the metal powder mixtures VSP-721 and KON-721 from Example 2 yielded comparable results. VSP-721 has a higher holding strength and higher sinter density than KON-721 at a predetermined sintering temperature when using the same initial density.

Example 4

Preparation of atomized powder VER-6525 (fraction: -65 + 25 μm) of the same composition as the porous bodies of VSP-721 and KON-721.

Previously prepared VSP-721 and KON-721 granules, and powder VER-6525 of the same composition and granular size as the granules produced by protective gas atomization (-65 / + 25) Handle in the way.

Each of the three grain types is first placed in three identical sintering pans (floor area: 6 cm × 2 cm: injection height: 3 cm). They are heated under hydrogen in a drying furnace at a rate of 2 K / min to a temperature of 600 ° C. for short circuits. This is followed by heating to 1250 ° C. at a heating rate of 10 K / min. The temperature of 1250 ° C. is maintained for 2 hours and the drying furnace containing the sintered body is then brought to room temperature at a rate of 10 K / min.

The formed (shrink) molded body is removed and evaluated by a three-point refractive test. This means that the shaped bodies have very different refractive intensities: VSP-721: 40 to about 20 MPa, KON-721; About 20 to 5 MPa, VER-6525: shows <5 MPa obtained. The relatively high sintering activity of variant VSP-721 thus allows the production of a sufficiently strong shaped body, for example for use in filter elements. Optimization of the sintering conditions allows the strength of the VSP-721 to increase above 50 MPa.

Example 5

Porous tube

Preparation of a tube-shaped porous body by sintering a high-density granule (VSP-721, KON-721) and a powder filling amount of a powder (VER-6525) prepared by atomization of the same chemical composition and particle size as this granule. Correspondingly prepared granules and approximately atomized molecules are each injected into a ceramic mold having a core that allows complete combustion. The core is in the form of a plastic thin tube that is sufficiently stable to withstand the pressure of the powder over its area after filling. It is filled with only a narrow granular or powder fraction (-65 + 25 μm) produced by the sieving.

In a subsequent step, the organic component and the inserted tube are removed by thermal decomposition or discharge in a drying furnace, while at the same time presintering starts at a high temperature (1000 ° C.). The pre-sintered body is then still vertically placed into another drying furnace reaching a temperature of 1300 ° C. at high gas purity (vacuum, pressure of 10 ⁻² mbar). After sintering, a molded body of VSP-721 with sufficient shrinkage and sufficient strength is obtained. The molded body of KON-721, on the other hand, has a lower strength. The molded body of the coarse powder (VER_6525) had a strength of only about 5 MPa under the conditions used, which is industrially unusable due to insufficient strength.

Example 6

Powder compact of high strength granule

The above-mentioned granular VSP-721 and KON-721 are injected into the cavity of the powder compression mold of the single screw press. Molded bodies having the following densities, namely VSP-721: 5.3 g / cm ³ (theoretical density 65%) and KON-721: about 6 g / cm ³ (theoretical density 73%), are produced in uniaxial pressing at a pressure of 700 MPs. The holding strength of the molded product of VSP-721 is 10 to 15 MPa, and the holding strength of the molded product of KON-721 is 2 to 5 MPa. After sintering according to the temperature-time program described in Example 4, the molded body of VSP-721 obtained 7.8 g / cm ³ (theoretical density 95%) and the sintered molded body from KON-721 was 7.7 g / cm ³ (theory). Density 94%). 5 shows a typical structure.

Example 7

Fluidized bed granulation for production of good fluidity and easy press powder

The processing of PZD powders (Nimonic® 90 according to Example 1) by fluid bed granulation (using the ProCell machine from Glatt) makes it possible to produce agglomerates having a particle diameter of 10 to about 300 μm. An aqueous suspension is produced which is injected into the fluidized bed chamber. When the ejected material dries, a small mass is formed first, which is deposited from several primary particles. They act as seeds for fluid bed granulation. Further separation and drying of the droplets produces lumps of increasing diameter. This growth process is accompanied by the impact between the growing particles, resulting in shrinkage of the surface. Due to the binder included in the suspension, the primary particles are bonded to the seed and the surface of the growing mass. Particle size and mass characteristics can be influenced by proper setting of flow conditions and air volume. The agglomerates prepared in this way have particularly good homogeneity of the components in single cell agglomerate grains.

Example 8

Preparation of coarse powder by condensation in wheat

By using pure Nimonic® 90 PZD powders having 10 μm d50 and 20 μm d90 prepared in the same manner as in Example 1, the main characteristics of very fine powders persist extensively (especially in sintering and pressing operations). It may be possible to carry out condensation.

Specifically, 600 g of PZD powder is added to the measuring vessel of the eccentric vibration mill. Steel balls of material 100Cr6 (DIN 1.3505) with a diameter of 15 mm are used. After milling for 1 hour at a speed of 1500 rmp in a milling vessel of argon 4.8, 80% ball filling level, 5 liter volume as the medium, the complete "rough" powder is removed from the mill. Particle size d50 is about 40 μm.

Example 9

Metal powder mixture with functional ingredients by spray drying

Preparation of granules that can be easily flown in the following way for use as thermal spray powders.

A spherically atomized Ni17Mo15Cr6Fe5W1Co alloy with an average particle diameter D50 of 40 μm commercially available under the trade name Hastelloy® C was exposed to the modification step described in Example 1.

Grinding of the formed flake shaped particles was carried out in an eccentric vibrating mill in the presence of tungsten carbide as a grinding aid according to the following conditions.

. Grinding container volume: 5 liters

. Ball charge: 80% by volume

. Grinding vessel material: 100Cr6 (DIN 1.3505)

. Ball material: Wc-10Co cemented carbide material

. Ball diameter: 6.3mm

. Powder weight: 150g

. Amplitude: 12mm

. Crushing atmosphere: Argon (99.998%)

. Processing duration: 90 minutes

. Grinding Aid 13.5 g WC (D50 = 1.8 μm)

In the prepared alloy-hard material composite powder, the alloy component is ground to an average particle diameter D50 of about 5 mu m, and the hard material component is ground to an average particle diameter D50 of about 1 mu m. Hard material particles were distributed very uniformly in the volume of the alloy powder.

1.5 kg of Hasrelloy C® PZD powder with 5 μm d50 and 10 μm d90 and 9.5 kg of tungsten carbide (d50: 1 μm, d90: 2 μm) were used for the preparation of VSP-712. The granulations were formed by treatment together by spray granulation as described in section 2. Variables for spray granulation were set to produce the minimum proportion of fine particles. To remove the portions that were not suitable for further processing (heat spraying), the particles with diameters larger than 65 μm were sieved and the rough portions were fed back into a susceptible suspension (mixed therein). Fractions with a diameter of less than 65 μm are shorted in a sintered boat with a floor area of 15 cm × 15 cm filled to a level of 3 cm, then shorted under hydrogen (heating at a heating rate of 2 K / min to 600 ° C.) and at 1150 ° C. Sinter. The sintered cake is removed after cooling and further processed by slight grinding in mortar. The micro-parts thus formed are classified into 50 μm sieves and 25 μm sieves. The fractions having particle sizes of less than 50 μm and more than 25 μm thus formed are applied by thermal spraying (high speed flame spraying) to Hastelloy C materials having low wear resistance as wear and corrosion resistant layers. Part of FIG. 6B includes the result of this coating. It can be observed that a homogeneous matrix alloy is formed which encloses the hard material particles and thus makes it possible to predict corrosion resistance and abrasion resistance. In contrast, the use of a rudimentary base powder (FIG. 6A) formed into granules in a similar manner to that for preparing sprayable powders results in heterogeneity in the layers produced. This can result in increased corrosion under conditions of a corrosive environment.

Example 10

Preparation of Easily Redispersible Spray Granules [LRDG]

Granules are prepared according to the method of Example 2. However, a mixture of benzene (about 10% by volume) and ethyl alcohol (about 90% by volume) is used as a solvent and polymethyl methacrylate (PMMA) is used as a plasticizer. Spray drying, which takes into account the conditions for handling highly combustible solvents, produces granules in which individual particles (Hastelloy C and tungsten carbide) form very strong bonds. The parameters for the spray granules are set such that coarse granules with good flowability (d50: 100 mu m, d90: 150 mu m) having a low content of fine particles are formed. By examining the individual narrower range of fractions by x-ray fluorescence analysis, one can quantitatively indicate that the same chemical composition and thus the same proportion of the powder components used are present in different fractions. Based on this, it can be concluded that the prepared granules are uniformly distributed since the separation of individual components of the fraction is not easy from a chemical point of view. Even after long periods of motion, such as when determining the density exceeding DIN EN ISO 787-11 or ASTM B 527, only a slight change in the particle size distribution occurs, resulting in a strong bond between the powder components used. It can be concluded that it was obtained in granules.

Example 11

Preparation of Powder-Containing Feedstock of Easily Redispersible Granules (LRDG) for Further Processing by Metal Powder Injection Molding

By stirring the granules prepared in Example 10 into alcohol, individual particles (Hastelloy C and tungsten carbide) can be released. The addition of waxes, polypropylene and stabilizers and the simultaneous application of high shear forces on shear rollers at sufficiently high processing temperatures makes it possible to obtain a homogeneous distribution of powdery functional material in an organic environment. Bubble-free compositions are processed into cold granules that are easily deliverable and uniformly soluble via the granulation system. It can then be added to the ejector system of the metal powder injection molding machine and heated and injection molded under the process parameters to be determined (temperature, pressure, pressure change, cooling time after compression, cooling time in injection molding, etc.). 80-95% of the organic components are extracted by solvent extraction from this injection molded part. Subsequently, heat residual short circuit by low-speed heating of a test piece under hydrogen is performed (heating of 1 K / min from room temperature to 600 degreeC). The part is pre-sintered at a temperature of 1000 ° C. under hydrogen in the same drying furnace. The sintering of these specimens is then completed in a vacuum drying furnace at a pressure of about 10 ⁻² to 10 ⁻³ mbar (heating at 5 K / min to 1250 ° C. at room temperature, lasting 2 hours at 1250 ° C., room temperature at 10 K / min Cooling).

Example 12

Preparation of components by cold powder rolling

The granules VSP-712 and KON-712 prepared in Example 2 were placed and compressed one by one into the nip of a vertical powder rolling machine. In the case of the VSP-712, this pressing takes place in easy-to-handle sheets having a holding strength of 2 to 10 MPa. For granule KON-712 it becomes impossible to remove specimens whose body strength can be reliably measured thereon.

VSP-712 sheets can be prepared by thermal post-treatment, short circuit and sintering as described in Example 11, which either becomes dense (93-98% of theoretical density) or porous (theoretical density: 60-60) depending on the sintering temperature selected. 90%). Despite the low density of the porous structure these sheets still have a high strength of at least 50-100 MPa.

Example 13

Construct-sheet preparation made by powder rolling

The granules VSP-712 and KON-712 prepared in Example 2 are short-circuited as the free powder charge and pre-sintered to stabilize (densify) the granules. This takes place under the conditions described in Example 5 for short / pre sintering at 1000 ° C. After cleavage dissolution comprising a fraction of -50 + 25 μm as described in Example 9, the granules formed thereby are treated with green ribbons in each case by powder rolling. The strength of the green ribbon is sufficient for further processing by sintering in the case of granules VSP-712. Fragments of KON-712 may not be suitable for further processing intended as a sheet. When the VSP-712 green ribbon is sintered at a temperature of 1300 ° C as described in Example 5, a density of 92% or more of theoretical density can be obtained.

Example 14

Parts manufactured by hot post densification by rolling

The green ribbon described in Example 13 does not necessarily have to be densified by sintering. A simple option for densification is to inductively heat the green ribbon to 1100 ° C. under an inert protective gas atmosphere (argon) before the green ribbon enters the roll nip and at which temperature the green ribbon is subjected to a strong pressure load. This will very simply produce sheet-like parts where complete densification (theoretical density:> 98%) or the desired residual porosity (theoretical density: 50 to 90%) can be set by varying the roll lip. Here, variant KON-712 has a lower body strength to obtain a sintered part.

Example 15

Parts produced by sheet molding, short circuit and sintering

A granule consisting of only Hastelloy C powder is prepared based on the method described in Example 10 and according to the method for producing an easily redispersible powder mixture. The tungsten carbide portion is omitted so that the sheet merely produces the sheet that makes up the alloy.

In the same manner as and in accordance with the process described in Example 11, a sheet formable, void-free composition is produced by strong grinding.

Such compositions are continuously applied to smooth surfaces by blade coating. Drying produces a metal powder filled sheet that is virtually green and has an organic component, such as rubber. This dough is now exposed to a short circuit by heating from room temperature to 600 ° C. at a heating rate of 0.1 K / min. This part is then exposed to sintering under the conditions described in Example 5 to increase strength. Linear densification typically occurs at this stage. This amounts to 10-25% depending on the sintering temperature and time.

Example 16

Parts with porosity set 'normally'

The green compact, prepared as in Example 15, is treated in a stamping tool in the form of a needle press (a stamp formed of needles of 0.1 to 0.5 mm diameter) such that the tubular variant remains perpendicular to the normal of its surface. .

After short-circuit and sintering under the conditions described in Example 5, a sheet constituting the dense material region and the porous channel located on the normal of the surface thereof is formed. Flow resistance can be easily set by the number and diameter of the channels without playing a direct role on the particle size of the powder particles, which can be important for the setting of certain corrosion and oxidation properties when using ultra fine powder particles.

Example 17

Mixture of VSP and Organic Position Holder for the Preparation of Micro Cell Porous Structure

Bubble-free feedstock with a `` honey-like '' viscosity are polymethyl methacrylate (such as 3.7 kg PZD powder (VSP-711) and 148 g powder (<30 ... 50 μm) in a kneader. PMMA), and a sufficient amount of a mixture of benzene (about 10% by volume) and ethyl alcohol (about 90% by volume) 0.67 liters of expandable polystyrene beads (1 to 1.5 mm in diameter) were added to the feedstock in the kneader. This composition (volume of about 0.9-1.1 liters) is placed into a flat ceramic mold (about 30 × 30 × 1.5 cm ³ ) and dried.The molded article thus produced is about 400 ° C. (0.5 K / min under hydrogen). The organic components (polystyrene position holder, PMMA, residual solvent) are removed by low temperature heating, and then the mold is heated at 5 K / min from room temperature to 1000 ° C. in the same drying furnace. ^-2 -10 ^-3 mbar) complete and pre-sintered test pieces 10K from room temperature to 1300 ℃ results in / min, and this temperature is maintained for 2 hours The volume of the fully sintered test piece is about 0.41 liters less than the initial volume (about 1 liter), which is equivalent to a linear shrinkage of about 26%. Resulted from the original 1 mm to 1.5 mm in the green state, which is equivalent to a decrease of 0.74 to 1.1 mm, with a material density of about 7.4 g / cm ³ obtained in the metal region.

Example 18

Mechanical Properties of Hot Compressed Fe22Cr7V0.3Y-Alloy

PZD powders were prepared as in Example 1 except that the atomized Fe 22 Cr 7 V 0.3 Y alloy was used as the vitreous (instead of Nimonic® 90 powder).

The treatable powder mixtures summarized in Table 3 are prepared in an Eirich mixer from PZD powders prepared accordingly and conventional spherical powders (-25 μm, −53 μm / + 25 μm).

Fe22Cr7V0.3Y powder with different content of PZD powder   Explanation Content of the relevant mixture (% by weight) PZD-718 [D50: 12 μm] KON-718 (F) (-25 μm) [D50: 13 μm] KON-178 (G) (-53 μm + 25 μm) [D50: 13 μm] 18.1 0 100 - 18.2 100 0 - 18.3 50 50 - 18.4 50 - 50

Prior to processing by hot forming, partial amounts of 18.2, 18.3, 18.4 are exposed to short circuits at a heating rate of 2 K / min from room temperature to 600 ° C. under hydrogen. Hot forming takes place under the following conditions: 1150 ° C./2 h / 35 MPa / argon 4.8 in a graphite mold. After hot forming, the temperature decreases by about 5-15 K / min until reaching room temperature. The disk thus produced has a diameter of about 100 mm. Tensile test pieces were prepared from the disc by water jet cutting as in Example 1 and polished to the same thickness (about 3.4 mm). All samples have material densities of 7.55 to 7.50 g / cm ^{3 which} are substantially the same. The results of the mechanical tensile test at room temperature are provided in Table 4.

Table 4 shows that the strength values Rp0.2 and Rm are better for all PZD powders including variants (Rp0.2: + 5-70% / Rm: + 20-50%). 18.1 has the best values for elongation (At-Fmax: elastic and plastic parts), and PZD-containing releases achieve At-Fmax values of 95-45%. Also in view of this fact, the variants 18.2, 18.3 and 18.4 are anyway processed by the basic advantages of the molding and sintering techniques, the metal powder mixtures resulting from the invention.

Results of mechanical tests (Rp0.2, Rm and At-Fmax) on hot pressed FeCrVY specimens  Explanation Mechanical properties (at room temperature) Rp0.2 [MPa] Rm [MPa] At--Fmax [%] 18.1 405 730 17.5 18.2 700 1100 8 18.3 430 870 16.5 18.4 480 870 15.5

Example 19

Mechanical Properties of Freely Sintered Fe22Cr7V0.3Y Powder Compacts

By mixing the powder mixtures 18.1, 18.2, 18.3, 18.4 listed in Table 3 with Licowax as molding aids, the powder mixtures 19.1, 19.2, 19.3, 19.4 are obtained. By using this, the molded body was formed in the form of a tensile test bar [A (area in the pressing direction): 6.35 cm ² , l (length in the pressing direction): 4-5 mm, p: 700 MPa by molding in the uniaxial direction. It is possible to get The amount of Licowax is selected in each case so that the shaped body comprises a total of 4% by weight of the organic component. This high content is only needed for releases 18.1 and 9.1 without PZD so that it is possible in any case to obtain a molded article with sufficient holding strength. In order to improve comparability, the residual powder is provided with the same amount of pressing aid.

After manufacture, the molded body was exposed to a short circuit (2 K / min from room temperature to 600 ° C.) under hydrogen. Subsequently, sintering occurs at four different temperatures (1290, 1310, 1340, 1350 ° C) under argon 4.8 in a low temperature wall drying furnace equipped with a Mo heater (manufactured by Thermal Technology). Heating is carried out at 10 K / min and the maximum temperature is maintained for 2 hours. After sintering, the test pieces were cooled to room temperature at a cooling rate of 10 to 15 K / min.

The results are summarized in the table below. Although great care was taken, the manufacture of 19.1, which can be tested at 1310 and 1340 ° C, was not possible. This is not because of the sintering temperature, but because of the shortcomings that occur after pressing, which is often not seen immediately, but often leads to breakage after a short circuit. This problem does not occur in 19.2 to 19.4.

It can be demonstrated that all the properties of the specimens 19.2, 19.3, 19.4 according to the invention are the same or better than the properties of the conventional powder 19.1 (as far as can be measured). At optimum temperature, Rm of + 40-130% (Table 5a), Rp0.2 of 5-45% (Table 5b), At-Fmax (Table 5c) of + 0-270%, density of 0-2% ( Table 5d) Improvements were obtained. Nevertheless, it is stated that the sintering process has not been optimized so far. Once the sintering process is optimized, the properties of 19.2 to 19.4 have a great advantage in reproducing the property because the tendency to become a 'pressing defect' is significantly lowered, and thus an improvement in the property can be predicted.

Effect of Sintering Temperature on Strain During Fracture of Freely Sintered Fe22Cr7V0.3Y Specimen Rm / MPa Sintering Temperature [℃] (2h, Ar4.8) 1290 1310 1340 1350 19.1 350 240 19.2 525 515 565 550 19.3 332 330 360 350 19.4 324 310 170 340

Effect of Sintering Temperature on Rp0.2 of Freely Sintered Fe22Cr7V0.3Y Specimen Rp0.2 / MPa Sintering Temperature [℃] (2h, Ar4.8) 1290 1310 1340 1350 19.1 290 215 19.2 410 380 425 335 19.3 290 295 305 300 19.4 280 275 290

Effect of Sintering Temperature on Elongation (At-Fmax) of Freely Sintered Fe22Cr7V0.3Y Specimen At-Fmax /% Sintering Temperature [℃] (2h, Ar4.8) 1290 1310 1340 1350 19.1 4 0.15 19.2 7 9 12 15 19.3 2 One 4 4 19.4 2 2 0.8 4

Effect of Sintering Temperature on the Density of Freely Sintered Fe22Cr7V0.3Y Specimen Density / g / cm3 (relative density: 7.5 / cm ³⁾ Sintering Temperature [℃] (2h, Ar4.8) 1290 1310 1340 1350 19.1 6.3 6.6 19.2 6.4 6.5 6.6 6.7 19.3 6.4 6.4 6.3 19.4 6.4 6.7 6.7

Example 20

Sintering Properties of Fe20C10Al0.3Y Alloy

PZD powder was prepared in the same manner as in Example 1. Instead of Nimonic® 90 powder, an atomized Fe 20 Cr 10 Al 0.3 Y alloy is used as the vitreous. The prepared PZD powder is referred to as 20.1 (PZD-720) and the reference powder is referred to as 20.2 (KON-720). Table 6 contains information on the treated powder mixtures. Licowax is used as a pressing aid.

'FeCrAlY' powder with 4% pressing aid Explanation Content of each mixture [% by weight] PZD_720 [D50: 15 μm] KON_720 [D50: 14㎛] PHM + Organic Ingredients [% by weight] 20.2 0 100 4 20.1 100 0 4

A tensile test bar (A: 6.35 cm ² , length (l): 4 ... 5 mm; p: 700 MPa) was prepared from the powders included in Table 6. Test pieces were made by wear cutting (in the pressing direction vertical direction) to measure perpendicular to the next pressing direction for dilatometer measurements. The measurement is in addition to slow heating at a heating rate of 2 K / min from room temperature to 500 ° C. for short circuiting, heating from 10 K / min to 1320 ° C. (duration time: 10 minutes), and 10 K / min from 1320 ° C. to room temperature. Cooling at a cooling rate. The results are shown in FIG. The heating rate is shown as the lower tin free curve, the curve for 20.1 is solid and the curve for 20.2 is broken. The results were collected in Table 7. The shrinkage paths show that the powder compacts of the conventional powder 20.2 are subjected to stretching within about 1290 ° C. as a result of the thermal stretching coefficient. There is no maximum shrinkage up to a temperature of 1320 ° C. To achieve this, the sintering temperature must be increased. However, the sinter shrinkage of PZD sample 20.1 already begins at about 1000 ° C. The first maximum shrinkage, not shown, occurs at about 1300 ° C.

This is consistent with the properties of conventional powders produced by atomization as disclosed in patent application PCT / EP / 2004/00736 and PZD powders produced there. It should also be noted that while 20.1 has a low starting density of 4.78 g / cm ³ (without organic components), a density of about 7.5 g / cm ³ is obtained after sintering. In contrast, a conventional test piece 20.2 obtains a density of about 5.7 g / cm ^{3 at} a starting density of 5 g / cm ³ . The advantages of sintered PZD powders therefore appear independent of their ability to produce powder compacts.

DIL (T, t) Sintering conditions (see note) Starting density [g / cm ³ ] Starting Density without Organic Ingredient [g / cm ³ ] Sintered Shrinkage (%) Sintered Density [g / cm ³ ] 20.2 5.00 4.8 5.84 5.7 20.1 4.78 4.6 15.17 7.5

Claims (18)

Particles of the base powder having a large or small average particle diameter are treated with flake shaped particles having a particle size to particle thickness ratio of 10: 1 to 10000: 1 in the deformation step, and these flake shaped particles are subjected to milling aids in further processing steps. When measured using a Microtrac® X100 particle size analyzer according to ASTM C 1070-01, obtainable by a process exposed to a grinder in the presence of an average particle diameter D50 of 75 μm or less, preferably 25 μm or less A metal powder mixture comprising component I, which is a metal, alloy and composite powder, component II, which is a conventional metal powder (MLV) to be applied to powder metallurgy, and component III, which is a functional additive. When the shrinkage of a metal, alloy or composite powder is measured using an dilatometer according to DIN 51045-1 within the point at which the temperature of the first shrinkage maximum is reached, a metal with the same chemical composition and the same average particle diameter D50 produced by atomization, Component I, which is a metal, alloy or composite powder, which is at least 1.05 times larger than the shrinkage of the alloy or composite powder and shrinks to a compressive density of 50% of the theoretical density before the powder to be investigated is measured, and conventionally applied to powder metallurgy. A metal powder mixture containing at least one of component II which is a metal powder (MLV) and component III which is a functional additive. 3. A compound according to claim 1 or 2, wherein components I and II, independently of one another, are identical or different and have a composition of formula I, hA- iB-jC-kD (formula Ⅰ) Here, A refers to one or more elements of the elements Fe, Co, Ni, B refers to one or more elements of the elements V, Nb, Ta, Cr, Mo, W, Mn, Re, Ti, Si, Ge, Be, Au, Ag, Ru, Rh, Pd, Os, Ir, Pt, C refers to one or more elements of the elements Mg, Al, Sn, Cu, Zn, D refers to one or more elements of the elements Zr, Hf, Mg, Ca rare earth metal, h, i, j, k are given as weight fractions, where h, i, j, k are independent of each other and mean 0 to 100% by weight, where h, i, j and k add up to 100% by weight Metal powder mixture, characterized in that. The method of claim 3, wherein A represents at least one of the elements Fe, Co, Ni, B refers to one or more elements of the elements V, Cr, Mo, W, Ti, C refers to one or more elements of the elements Mg, Al, D is a metal powder mixture, characterized in that it refers to one or more elements of the elements Zr, Hf, Y, La. The method according to claim 3 or 4, wherein h is 80% by weight, i is 15 to 40% by weight, j is 0 to 15% by weight, k means 0 to 5% by weight, and h, i, j and k add up to 100% by weight of the metal powder mixture. The method according to claim 1 or 2, wherein component I and / or component II are Fe20Cr10Al0.3Y, Fe22Cr7V0.3Y, Ni17Mo15Cr6Fe5W1Co, FeCrVY, Ni20Cr16Co2.5Ti1.5Al, Ni53Cr20Co18Ti2.5Al1.5Fe1.5 and Ni57Mo17Cr16FeWMn The metal powder mixture being the selected alloy. The metal powder mixture according to any one of claims 1 to 6, comprising conventional processing aids or pressing aids. 8. The metal powder mixture according to claim 1, which is a mixture of component I and component II. 9. The metal powder mixture according to any one of claims 1 to 8, which is a mixture of component I and component III. The metal powder mixture according to any one of claims 1 to 9, which is a mixture of components I, II and III. The metal powder mixture according to any one of claims 1 to 10, wherein the component III comprises a hard material, a slip agent or an intermetallic compound. 12. The composition of any one of claims 1 to 11, wherein component III is carbide, boride, nitride, oxide, silicide, hydride, diamond; Carbides, borides and nitrides of elements of groups 4, 5, and 6 of the periodicity, oxides of elements of groups 4, 5, and 6 of the periodicity, oxides of aluminum and rare earth metals; Silicides of aluminum, boron, cobalt, nickel, iron, manganese, molybdenum, tungsten, zirconium; Hydrides of tantalum, nionium, titanium, magnesium and tungsten; Graphite, sulfide, oxide, molybdenum sulfide, zinc sulfide, tin sulfide (SnS, SnS ₂ ), copper sulfide; A metal powder mixture comprising boron nitride, titanium boride and an intermetallic compound having particularly magnetic or electrical properties on a rare earth-cobalt or rare earth iron base. 13. Metal powder according to any one of the preceding claims, comprising as component III long chain hydrocarbons, waxes, paraffins, plastics, fully degradable hydrides, refractory metal oxides, organic and / or inorganic salts. mixture. The low molecular weight polyethylene or polypropylene, polyurethane, polyacetal, polyacrylate, polystyrene, rhenium oxide, molybdenum oxide, titanium hydride, manganese hydride according to any one of claims 1 to 13. And a metal powder mixture comprising tantalum hydride. A process for producing a shaped article, wherein the metal powder mixture according to any one of claims 1 to 14 is exposed to a powder metallurgy molding process. The method according to claim 15, wherein the powder metallurgy forming process comprises pressing, sintering, slip casting, sheet casting, wet spraying, powder rolling (cold, hot or moderate temperature powder rolling), especially with green processing, heat spraying and weld welding. Hot forming and hot isostatic pressing (HIP), sintering HIP, powder charge sintering, cold isostatic pressing (CIP). Molded article obtainable by the process according to claim 15. A molded article comprising the powder mixture according to claim 1.

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